1. Field of the Invention
The present invention relates to a method for Manufacturing electroluminescent display device, and more particularly, to a method for manufacturing cathode electrodes of electroluminescent display device capable of forming cathode electrodes having fine patterns.
2. Description of the Related Art
As a next generation display, self-luminescent organic electroluminescent (hereinafter referred to as EL) devices have a structure that an anode electrode, an organic thin film layer and a cathode electrode are sequentially deposited on a transparent substrate. In the passive matrix panel, the size of pixels depends on the line width of cathode electrodes and anode electrodes crossing each other and in order to obtain high resolution organic EL panel, anode pixel electrodes and cathode metal layers are formed to have a fine pattern. The pixel electrodes accomplish the fine pattern by using lithography process and the cathode electrodes by using shadow mask or by forming cathode separation partition without mask.
However, it is difficult to pattern the cathode by using the cathode separation partition since a Japanese organic panel maker, pioneer has a patent right for the method.
FIGS. 1A and 1B are cross-sectional views for showing a conventional method for manufacturing cathode electrodes of electroluminescent display device.
Referring to FIG. 1A, first, a transparent insulating substrate 11 is prepared, wherein an anode electrode 12 and an organic film layer 13 are formed in a stripe shape. Then, a shadow mask 14 is provided to form succeeding cathode electrode pattern on the organic film layer 13.
Referring to FIG. 1B, the transparent insulating substrate 11 including the anode electrode 12 and the organic film layer 13 is put into a vacuum deposition device, the organic film layer 13 being downward. Subsequently, evaporated metal ions are deposited on the transparent insulating substrate 11 having the shadow mask 14 from a metal source unit S on the lower part of the vacuum deposition device and then, pattern etch is performed to obtain a cathode electrode. As a result, the fabrication is completed for electroluminescent display device as organic EL device.
FIGS. 2 and 3 are cross sectional views for showing problems of conventional methods for fabricating cathode electrodes of electroluminescent display device.
The conventional methods for fabricating cathode electrodes of electrolumnescent display device will be described referring to the FIGS. 2 and 3.
First, according to the conventional method for fabricating cathode electrodes by using shadow mask, it is required to maintain accurate contact of alignment of shadow mask and transparent insulating substrate with shadow mask. Therefore, as the size of pixel becomes small and that of panel is increased, it is difficult to be used due to misalignment of shadow mask and inaccurate contact of transparent insulating substrate and shadow mask.
Second, as shown in FIG. 2, metal ions evaporated by the misalignment are flowed into the gap L between the shadow mask 14 and the organic film layer 13, thereby generating shorts with the anode electrode 12.
Finally, as shown in FIG. 3, when the transparent insulating substrate 11 having the shadow mask 14 is put into the vacuum deposition device, the center of the shadow mask 14 is hanging down due to the large panel, thereby generating shorts with the cathode electrode and the anode electrode. Therefore, there are problems that the shadow mask should be formed with a material having strong magnetism and additional devices are required to tightly support the shadow mask on all sides.
Therefore, the present invention has been made to solve the above problems and the object of the present invention is to provide a method for manufacturing cathode electrodes of electroluminescent display device capable of forming fine pattern cathode electrodes using laser.
In order to accomplish the above object, the present invention comprises the steps of: providing an anode electrode on a transparent insulating substrate; forming a separation partition having a stripe structure to cross with the anode electrode and define a pixel formation area on the substrate; forming organic film pixels separated from each other with insulating partition interposed; depositing a cathode metal layer on the surface of the resulting structure; and performing etching processes on the cathode metal layer by using laser to form a cathode electrode exposing a predetermined part of the insulating partition.
The etching process using laser is performed to remove the cathode metal layer by rotating the laser downward from a horizontal axis in the range of 0xcx9c180xc2x0. Here, the laser is controlled in a rotation manner.
And, the etching process using laser is performed by moving back and forth with the laser fixed vertically downward.
The absorbent is BaO or Y2O3 of oxide series.
After the cathode electrode is formed, the present invention further comprises the steps of: forming absorbent between cathode electrodes on the insulating partition to prevent humidity; applying UV hardening resin for protection on the upper part of edge of the insulating partition; and forming capsule on the upper part of the UV hardening resin.